1. Field of the Invention
The present invention pertains to a method and apparatus for treating sludges containing solids and relatively heavy hydrocarbonaceous liquids of the types typically existing in crude oil transport and refinery operations, for example.
2. Background
In the continuing effort to recover hydrocarbons and prepare waste materials from various operations involving hydrocarbon fluids for disposal in accordance with environmentally safe practices, several problems remain in connection with the suitable disposal of waste substances generated in crude oil refinery operations, cleaning and refurbishing oil storage tanks and cleaning and treating storage tank wash down solutions and marine tanker ballast, for example.
In my prior application referenced hereinabove, an improved method and apparatus has been developed for treating slurries containing oil, water and solids such as are generated in the drilling of subterranean wells. In treating well drilling fluids, for example, the slurry that results from the drill cuttings separation process can be suitably treated by introducing the slurry to an indirect dryer apparatus and distilling or vaporizing the liquids, primarily comprising water and refined petroleum liquids which have been purposely added to drilling fluids. The temperatures at which conventional indirect dryers may operate suitably provide for vaporization of the oils used in oil based drilling muds, for example, so that the dried solids discharged from the indirect dryer are substantially free from the hydrocarbonaceous materials. Moreover, these solids are typically materials that have been withdrawn from the earth and have not been previously treated or converted into materials which are toxic or otherwise harmful.
However, in a continuing effort to develop suitable treatment processes for handling and converting waste materials from refinery operations, oil storage tanks, marine tankers and other sources, it has been particularly difficult to convert all of the hydrocarbon materials and to provide conversion of solids in these wastes into relatively harmless materials. For example, many oil refinery waste streams include relatively heavy residual hydrocarbon substances which cannot be distilled at atmospheric conditions below temperatures of about 700.degree. F. Refinery waste sludges, storage tank sediments and sludges, and marine tanker ballast water solutions, for example, also often contain quantities of relatively toxic solids of heavy metals such as chromium, vanadium, nickel and other materials which cannot be returned to the environment safely using the processes described in the abovereferenced application or other prior art processes.
Accordingly, the present invention is directed to a method and apparatus for distilling heavy oil sludges such as refinery waste streams, storage tank residual sludges, and marine tank ballast water solutions to distill the water and oil substances present in these materials and to convert the solid materials into oxides of the materials themselves and which are substantially free of any hydrocarbonaceous materials.